I have to say Duskshipping makes absolutely no sense at all, there is no evidence that supports Felix and Karst ever being a item.

There is however a random Proxian girl who develops a crush on Felix, using mind read you will see that she says quote Felix is hot stuff, then notice that she keeps staring at Felix as he walks around.

Also the Item shopkeeper if mind read is used she says about Felix being a son in law, this can't be referring to Menardi and Karst because of two reasons, first being nothing being confirmed about the Shopkeeper being Menardi and Karst's mother, and second Karst and Menardi are already dead and she's thinking of Felix marrying her daughter in the future.

Also I think possibly Karst and Saturos should be a legit pairing, same goes with Agatio and Menardi.

Karst may of hid how she felt about Saturos being killed by Isaac in the shadow of her sister being by Isaac for a couple reasons, one she didn't want to show weakness in her love for Saturos, so she channels it in her fury about her sister being killed instead.

Another thing, maybe Agatio was even more furious at Isaac than Karst was for killing Menardi.

Then with Agatio and Menardi, maybe Agatio and Menardi were a item, Agatio seemed to want to avenge just as much as Karst, if not more example the part on Jupiter Lighthouse when Karst says maybe they should retreat and Agatio refuses, why?

Was Menardi and Agatio a item?

Nothing confirmed of course, but it bothers me these two Shippings aren't being addressed by the fanbase.